Anaesthetic works its way through a tube attached to his abdomen and she kisses his forehead repeatedly until his tiny body goes limp.

"You'll feel better later, OK," she whispers. "I'm sorry."

She holds her son a little longer. The medical team knows the routine. They tell her Edric will be OK and she lays him down gently and reluctantly leaves the room.

It is the sixth time Rochelle has had to do this but it has not got easier. As she walks away from the gantry - an imposing room-sized cylinder that is about to shoot proton beams into the tumour invading her son's skull - she struggles not to weep.

"It's like I leave him behind," she said. "Like I have forsaken him. But I know it is for him."

It has been just over two weeks since Rochelle and her husband Edwin Ho packed what they could from their Brentwood home and flew to the US in a bid to save the life of their youngest child.

The journey has taken them to Jacksonville, Florida - a city with stifling humidity, a footprint bigger than any other city in the US and, critically, the treatment they believe is their son's best chance of survival.

For 33 days, the heartbreaking sight of their son going under general anaesthetic will be their morning routine.

18 month-old Edric Ho's parents - Rochelle Luke and Edwin Ho - wait for their son to wake up from his anaesthesia. Picture: Steve Pennells/The West Australian

Rochelle walks back to Edwin in the waiting room at the University of Florida's Proton Therapy Institute and they sit quietly together until Edric is wheeled out 40 minutes later.

"We have entered a world that's different . . . it's no longer normal," Edwin says, trying to explain the surreal bubble that has enveloped them - a hopeful, prayerful, self-funded, all-encompassing determination to save their son.

"We are shocked sometimes that we are still waking up thinking that this is a dream. We view the world differently now because we were put into a world where, at the moment, every family has got a sick child."

They nod to nearby parents they recognise from their temporary home at Ronald McDonald House, a short drive across the river that cuts through the city.

It has become their sanctuary in an unfamiliar country and an unfamiliar world.

"It's like the UN here," their new friend Corina Secareanu explains in a thick Romanian accent in the lounge of the building where 30 families are united by shared heartache. "There are people from everywhere."

Everyone is in the same boat, she says. Except for the Hos. They're the only family in the building who aren't being supported by their Government.

"I thought Australia was a civilised country," Ms Secareanu says, shaking her head and reaching out to her son Adrian, 12, who has had part of his jaw removed because of an aggressive form of cancer. "I can't believe it."

She said the news that the Hos had to self-fund their son's treatment shocked her.

In a surprise decision a few weeks ago, the Ho family were knocked back for funding under the Federal Health Department's Medical Treatment Overseas Program on the grounds Edric could have more standard treatment, known as conformal photon radiotherapy, in Australia.

The decision came despite recommendations from his doctors, including a Sir Charles Gairdner Hospital radiation oncologist who has backed their appeal and said there is no comparable treatment in Australia. Edric's best hopes lay in the US, he said.

So the Ho family were forced to remortgage their Perth home and begged and borrowed from family and friends to raise $200,000 so Edric could have targeted proton beam therapy in Florida to treat his aggressive brain tumour known as anaplastic ependymoma.

Unlike conventional photon therapy, proton therapy minimises damage to healthy cells by delivering a powerful punch of radiation right to the tumour site.

Because the beams can be more tightly controlled, doctors can prescribe higher doses of radiation with less impact on the health of surrounding tissue.

"We have no regrets that this was the right thing to do," Edwin says as Edric's three-year-old sister Ethel rubs her brother's hand gently to wake him up.

The next morning, when they return to repeat the process, Edric is irritable. "It's the fasting," Rochelle explains. "He can't eat six hours or drink three hours before each treatment."

Edwin wants his son back. "Before he had what he had - before he had cancer - he was a very contented boy," he says.

"We don't know what's happening in his head. And I think he is a different character than he was before. There are days with ups and days with downs. But he deals with it very well. As much as an 18-month-old boy can."

In the foyer of the institute, a set of chimes hangs from the ceiling. They were donated by the mother of the first Australian patient to be treated at the centre.

When each cancer patient finishes their last treatment session, they get to ring the chimes.

The sound of hope echoes through the corridors.

Edric will pull on the rope in a month. "That will be a good day," Edwin says.